TM 11-5840-360-14-1-1
SECTION V: RF TEST PROCEDURES
8. Calculate transmitter peak power (20 kW
minimum) as follows:
5.22 GENERAL
This section contains procedures for making RF
Average Power Recorded In Step 4
measurements which require use of test equipment
Peak Power = Duty Cycle Calculated in Step 7
which is permanently installed external to the AN/ SPS-
64(V) Radar Sets. The procedures are divided into X-
5.23.2 Receiver Sensitivity
(Minimum
Discernible
band test procedures (paragraph 5.23) which are
Signal- MDS) Measurement
applicable to all AN/ SPS-64(V) Radar Sets and S band
test procedures (paragraph 5.24) which are applicable to
1. Set (master) Indicator POWER switch to ST BY.
AN-SPS-64(V)4 installations only. Procedures for power
2. Calibrate signal generator (HP 620E or
output, receiver sensivity (MDS) and antenna VSWR
equivalent) output power level at 9420 MHz per its
measurements are provided for both X band and S-band
instruction manual.
equipments, measurement of transmitter frequency is
3. Set signal generator controls as follows:
covered-e for X band equipment only.
a. Frequency: 9420 MHz
b. Modulation: Internal pulse, 0.5 us-c width,
5.23 X BAND RF TEST PROCEDURES
1800 Hz PRF
5.23.1 Peak Power Output Measurement
c. Output Level: -67 dBrm
4. Connect signal generator RF output to
1. Attach 20 dB attenuator (Weinschel Engineering
FORWARD port of directional coupler using six foot RG
model 530A 20 or equivalent) at FOR WARD port of 20
214/U coaxial cable (supplied with HP 620E) .
dB Directional Coupler (located in the waveguide run
near the output flange of Receiver Transmitter RT-
NOTE: The loss of six feet of RG 214,
1240).
J coaxial cable is approximately 2.4
2. Connect thermistor mount (HP 478A or
dB at X-band frequencies.
The
equivalent) of power meter (HP 432A or equivalent) at
actual loss of the test cable should
output port of 20 dB attenuator.
be measured at 9420 MHz.
3. At (master) Indicator associated with Receiver
5. Connect oscilloscope at receiver output
Transmitter RT-1240 under test, set POWER switch to
connector A1600J1 in Receiver Transmitter RT 1240;
TX ON and RANGE SELECT switch to 24 MILES.
trigger oscilloscope from signal generator.
6. Adjust signal generator attenuation and(l
NOTE:
The
values
given
in
frequency controls to identify test video signal on
parentheses in the following steps
oscilloscope; set attenuation control for non-saturating
indicate the nominal values that
test signal and carefully adjust frequency vernier to
maximize test signal amplitude.
should be obtained.
4. After 3.5 minute delay, observe power meter
7. Increase signal generator output attenuation
4
reading (1.8 mW or greater); multiply read ing by 10
setting until test signal is just visually discernible in the
(attenuation factor) and record result as average power
displayed noise.
(18 W).
5. At Receiver Transmitter RT 1240 connect
NOTE: Adjustment of the signal
oscilloscope to U4 pin 6 on A1100 Pulse and Driver
generator delay control will aid in
PCB.
identifying the test signal at the
6. Measure pulse width (PW) and pulse repetition
threshold of discernibility.
time (PRT) from oscilloscope display; record both in
8. Verify MDS, calculated as follows, is less than
terms of seconds (PW = 1 x 10 x 10-6 sec, PRT -1.11 x
or equal to 98 dBm.
MDS (Signal Generator
-3
10 sec).
Attenuation) - (Directional Coupler Attenuation) (Test
7. Calculate radar duty cycle (0.0009) as follows:
Cable Attenuation)
Duty Cycle =PW
NOTE: For 20 dB directional coupler
PRT
loss and 2.4 dB cable loss, the signal
generator must be set to -75.6 dBm
or less for an MDS of -98 dBm.
5-119
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